It is known to make pellets of plastics material by melting the material and forcing the molten material through holes in a die member into a region where the plastics material is cooled to cause it to solidify, the cooled strands of extruded material being severed by cutting means, to form pellets. A known machine for carrying out this method comprises a cylindrical extrusion chamber in which an extrusion screw is mounted for rotation, a die member such as a pellet plate forming a wall across one end of the extrusion chamber. Plastic material to be pelletized is supplied to the chamber at one end and is plasticized by rotation of the extrusion screw (and, if necessary, application of a controlled quantity of heat), the screw forcing the molten plastics material through holes in the die plate at the other end of the chamber. In such a machine the cutting means may conveniently comprise a rotating knife which runs on a front face of the die plate to sever the plastics material extruded through the holes therein. In a known machine the die holes are disposed in an annular portion of the pellet plate, a central portion of which is supported by means disposed outside the extrusion chamber against displacement by pressure of plastics material in the extrusion chamber. A cone torpedo coaxial with the screw is secured to the central portion of the pellet plate to assist flow of molten plastics material towards the perforated annular portion of the pellet plate. It has been found that a stagnant region tends to form at the end of the extrusion screw, and material entering this stagnant region becomes overheated. Where the material is a straightforward thermoplastics material, overheating causes the material to degrade. Bits of the degraded material from time to time enter the flow of plastics towards the holes in the pellet plate and block the holes and/or cause the pellets of plastics material produced to be of an inferior quality. Where the plastics material being processed is a thermosetting type of material, (that is, material which can in its uncured state be rendered molten by the application of a controlled quantity of heat but which upon application of heat beyond this controlled quantity sets to a hard condition in which application of heat cannot melt the material) it has also been found that cured material tends to build up at the end of the screw to such an extent that flow of molten material to the holes in the die plate is severely restricted or even blocked altogether.